Is This Cute Video Just a Rat Loving a Cat, or the Beginning of the End of Toxo

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January 5, 2009

Is This Cute Video Just a Rat Loving a Cat, or the Beginning of the End of Toxo

A lot of people probably look at the video I’ve posted below and think, Awh, it’s a hilarious rat who just loves his friend the cat! But when I watch it, I can’t help imagining something evolutionarily larger.
Some background information: The parasite Toxoplasma infects many species (including an estimated 60 million people in the US), but it can only undergo sexual reproduction in cat digestive tracts. Evolutionarily speaking, this means toxo’s survival depends 100% on its host being eaten by a cat (even if its host is human; more on that below the jump). So toxo has evolved a complicated system for taking over its hosts’ brains to increase the likelihood that they’ll be eaten by cats (for example: it rewires rat brains so they’re actually attracted to the smell of cat urine). Knowing this, I ask you: Is this rat just friends with this cat? Or is it actually in a toxo induced frenzy and trying to get eaten? If so, then this video is an example of a cat kicking toxo’s ass (to a hilarious soundtrack):

If all cats were like this one, toxo would eventually cease to exist.
Now, on a more human note …

Last year, I wrote an article questioning whether all of this might explain the ubiquitous Crazy Cat Lady syndrome: Maybe their obsessive cat collecting is actually a sign that toxo has taken over their brains and is making them hoard cats to increase the likelihood that they’ll be eaten by one. So far, no one has studied that theory.
Thanks for the video link, Meg, though your peeps may not want to think about this one ;-).
[Update: Those entertained by the idea of a toxo infected rat desperately trying to get eaten by a cat should check out my pal Scott Westerfield’s book Peeps, which features a such a toxo-infected rat (plus vampires and other fun things).]

24 Responses to “Is This Cute Video Just a Rat Loving a Cat, or the Beginning of the End of Toxo”

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tim says:

January 13, 2009 at 12:28 am

One problem with your hypothesis about toxoplasma and CCL syndrome is that a very large fraction of the population is infected with toxoplasma. You are probably infected, even if you live in a developed country like the US. I don’t have a reference, but once looked into this and read a whole bunch of stuff about toxoplasma, and in developed countries some huge number like %40 of humans are infected by age 12. I don’t see why the infection rate would go down a whole lot as you get older, so the adult population must have a very high infection rate, though I remember reading that it is not very well known what it is.
Toxoplasma is one of the most common and successful orgarisms around, and is very common in the soil (as one type of cyst that resists cooking and water) and also meat, especially pork. You can find studies that investigate how common it is in various types of meat.
Even pre-cooked ham is still sometimes infectious. It’s easy to vaccinate against, though, and it is easy to destroy in meat with gamma treatment. People should have the option of getting vaccinated if they want to. The infection can also be cured. Personally I would like to be cured….. If I had the money I might look into it :-(. It wouldn’t hurt.
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alayna says:

January 9, 2009 at 12:26 pm

On the lighter side, as a lesbian, could any of you scientifically explain why I have noticed it is mostly gay women I have known that posses this problem 🙂 Perhaps 5 or 6 cats doesn’t officially qualify as crazy cat lady syndrome to some, but that looks toxo crazy to me!
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Maija Karala says:

January 9, 2009 at 12:21 pm

The “hugs and kisses” the rat gives to the cat on the video don’t look like normal behavior – but that’s exactly what my pet rats do to me and almost all other people they happen to meet. They are not exactly scared of small dogs either, so I think they would probably like a cat as much.
I’d say the rats’ behavior is completely normal, but I’m not that sure about the cat.
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Maija Karala says:

January 9, 2009 at 12:19 pm

The “hugs and kisses” the rat gives to the cat on the video don’t look like normal behavior – but that’s exactly what my pet rats do to me and almost all other people they happen to meet. They are not exactly scared of small dogs either, so I think they would probably like a cat as much.
I’d say the rats’ behavior is completely normal, but I’m not that sure about the cat.
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catharine says:

January 8, 2009 at 10:30 pm

I learn more medicine from the internet than I ever did in medical school
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Laurent says:

January 8, 2009 at 6:16 am

Otherwise, toxo contamination from rodents to cats can happen in other ways than prey eating, so I’m not sure this would be the end of toxo at all.
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Laurent says:

January 8, 2009 at 6:14 am

It is apparently frequent that cats won’t hunt animals that belong to their ‘nesting’ territory. I’m told for years even if I always find it difficult to believe. My partner’s cat never killed any mice that happened to move onto the boat, despite she was a quite famous hunter on the shore. To the great deception of the other boat inhabitants (but the rodents).
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MattK says:

January 7, 2009 at 9:50 pm

Problem with the non-experimental protocol: hoarding cats may cause toxoplasmosis since it obviously provides greater opportunity for infection. Guess we’ll have to go experimental.
Toxoplasma was what killed the one of the characters in Train Spotting (but he had AIDS and so was immunocompromised). Toxoplasma can also be very dangerous to human fetuses if their mothers newly acquire an infection while pregnant.
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Rebecca Skloot says:

January 7, 2009 at 1:46 pm

Frasque and others curious: Scott Westerfield’s book Peeps is totally related to all of this. I mistyped above when I said the toxo in his story didn’t come from cats … of course, all toxo comes from cats at some point, since that’s where it reproduces. I meant that his character who was running around trying to spread toxo wasn’t a cat. It was, in fact, a rat … … you can learn more here (hi Scott!).
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Dave says:

January 7, 2009 at 10:44 am

It should be mentioned that most cases of toxoplasma infection are not directly from cats, but from eating undercooked meat of intermediate hosts or from (presumably accidental) ingestion of cysts in the soil.
So they may be cat ladies now, but they probably got that way from not washing their hands after gardening.
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Rebecca Skloot says:

January 7, 2009 at 10:15 am

Yep, Frasque, toxo is spread directly from cats, which is why cats loving rodents would be a big problem for toxo. In order for toxo to reproduce then infect other species, it has to be inside a cat first. It can (and does) live just fine in any species, Christopher, it just can’t reproduce in any but cats for some reason.
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Maureen Lycaon says:

January 7, 2009 at 12:35 am

Er, Frasque: Crazy Cat Collectors (people who hoard literally dozens of dogs or cats without regard to their ability to care for them) usually aren’t concerned at all with the pets’ welfare. Ask any Humane Society or animal-shelter workers who’ve had to deal with them when the problem finally went to the health department or the police.
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Skloot says:

January 6, 2009 at 12:27 pm

EdY! I’ll buy you MRSA if you buy me Toxo …
@Pierce: Yes, actually, it is seen in men (though not as commonly). Also not limited to cats …
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Pierce R. Butler says:

January 6, 2009 at 12:15 pm

Is Crazy Cat Collector Syndrome also observed in human males?
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Frasque says:

January 6, 2009 at 10:47 am

Maybe I’m misremembering, but I thought the infection was passed directly from cats, and while it didn’t cause hoarding it did make the victims really over-concerned about the health and welfare of the cats . . . of course, real toxo doesn’t turn people into vampires, either. *shrug*
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Rebecca Skloot says:

January 6, 2009 at 9:39 am

I see a lot of promise in the study being developed here. Warms my heart.
@Pat: Toxo has been more than anecdotally linked to behavior changes in humans. My favorite studies are the ones linking toxo to increased car accidents in humans (here and here). Especially when it comes to . It’s just that no one’s looked at its connection to Crazy Cat Lady Syndrome.
@Frasque: Scott’s book actually predates my theory. His plot is pretty different from this toxo theory, since his craziness isn’t specifically caused by cats and doesn’t involve cat hoarding. But I’m sure I wasn’t the first to wonder about this.
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Pat McComb says:

January 6, 2009 at 9:08 am

Thanks for posting this. My cat, Al, was playing with a mouse recently. Al has killed mice before, but would not kill this mouse. In fact, the mouse made no effort to escape. After a game of tag, the two of them just stared at each other. I wondered if this was adaptive on the cat’s behalf — don’t eat any critters that are too easy a catch.
I’ve wondered about Crazy Cat Lady syndrome and toxo also. I’d heard that toxo has been (albeit anecdotally) linked to other behavioral changes in humans and may even create symptoms similar to schizophrenia.
I’m surprised a thoroughgoing study of toxo in humans hasn’t happened yet.
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Ed Yong says:

January 6, 2009 at 8:39 am

You can get some toxo of your own: http://www.giantmicrobes.com/us/products/toxoplasmosis.html
More seriously, Kevin Lafferty’s done work on the effects that Toxo has on human behaviour on an international scale. Obviously, very controversial, but REALLY interesting.
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Ward S. Denker says:

January 6, 2009 at 7:35 am

Knowing this, I ask you: Is this rat just friends with this cat? Or is it actually in a toxo induced frenzy and trying to get eaten?

As someone that’s had kept many rats as pets over the years, I can say that the former is a real possibility.
The rats in the video probably been socialized with people (and the cat) since birth. The more socialization they get with humans and other animals the less timid they become. They’ll do things no (uninfected) wild rat will do, like chase other animals and play with them like they play with one another.
Those are some cute little guys in the video!
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Frasque says:

January 6, 2009 at 3:13 am

That was YOUR theory? Then do you know you inspired a YA book titled “Peeps” by Scott Westerfield? in the book the Toxo-type parasite turns people into vampires (sort of) but cats form an important link in the whole chain.
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Bob O'H says:

January 6, 2009 at 1:43 am

Dave – you’d also need to infect some women to see if they turn into cat ladies. That could be a fun application to write to the ethics board.
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christopher guerra says:

January 6, 2009 at 12:49 am

i was just wondering if the toxo parasite like to live in humans or does it get stuck there on accident?
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Dave says:

January 5, 2009 at 6:15 pm

Your cat lady hypothesis could be tested relatively straightforwardly, I think. First you would have to come up with a clinical definition of ‘cat-lady syndrome’ sufficient to decide unambiguously whether or not someone was a ‘cat lady’ or not. Then you need to get the brains of these cat ladies, along with brains from age & lifestyle-matched controls. Then you check for toxoplasmosis cysts in the brains of both groups. The null hypothesis is that cat ladies and control ladies will have the same incidence and severity of toxoplasmosis infection.
If cat ladies tend to be more infected (e.g. p for the results in the experiment above turns out to be less than 0.05), then the next step is to test whether anti-toxo drugs bring them back to their senses.
Easy peasy. For a million dollars, I’ll work on it for ya. Or (more likely) subcontract the study. I don’t want to have to write the human experimentation protocols.
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jabfish says:

January 5, 2009 at 5:55 pm

ooh. I completely agree with your toxo-CCL syndrome hypothesis. The CCLs must either carry some resistance to toxo or get infected by a less virulent strain of the bug to explain their long life spans.